Advertisements

Posts Tagged ‘Google Earth’

Descargas del CNIG. Open Source bien hecho!

2016/02/08

Hola amigos del GIS,
Por motivos de trabajo que no vienen al caso, he tenido que bucear de manera sistemática la web de descargas del CNIG. http://centrodedescargas.cnig.es/CentroDescargas/inicio.do
Una maravilla.

cnig-20160208-01

Por motivos que tampoco viene al caso, he de hacer esto mismo de vez en cuando en todos los Institutos cartográficos del mundo y el del CNIG es sin duda en el que me resulta más fácil, en el que el modelo de datos en más lógico y en el que los links son más fiables de todo el mundo. La única obligación es la atribución obligatoria de los datos. ¿No es mucho pedir, no? Desde el día 27 de diciembre, los datos del IGN son libres CC By 4.0.
https://creativecommons.org/licenses/by/4.0/

Por tanto es obligatorio que mencione la procedencia a pie de imagen, créditos, etc.., sobre todo en publicaciones, usos comerciales, artículos, etc… (Por ejemplo puede poner “<tal dato> CC by instituto Geográfico Nacional” o más bien “derivado de <tal dato” CC by ign.es” o similares…).

cnig-20160208-02

Ya sea porque necesitemos las imágenes del PNOA (Plan Nacional de Ortofotografía Aérea), un modelo digital del terreno de alta resolución o imágenes históricas de nuestro pueblo… tan solo hay que bucear un poco en el catálogo de geodatos del Instituto Geográfico Nacional (Centro Nacional de Información Geográfica) y los conseguiremos.

Por ejemplo, la semana pasada tuve que encontrar datos sobre algunas ciudades españolas para hacer varios escenarios 3D para un cliente y aquí encontré por un lado un DSM 5m elaborado con fuentes LIDAR, por otro lado me bajé de Cartociudad los datos relativos a vectores lineales, manzanas y luego desde la web de CATASTRO (https://www.sedecatastro.gob.es/OVCFrames.aspx?TIPO=TIT&a=masiv) me bajé las geometrías de todos los edificios de la ciudad (que planeo geoprocesar para eliminar las formas no deseadas y para adjudicar alturas precisas gracias al LIDAR bajado con anterioridad).

Por qué no añadir geometrías de Open Street Maps (https://www.openstreetmap.org/export) o de la propia Base Topográfica Nacional BTN25 para completar dicho escenario?

barcelona-bldg-osm-capture-20160112
MADRID-GISDATA

La verdad amigos es que desde que empezó a funcionar el Open Data, los Geógrafos y derivados tenemos mucho con lo que ‘jugar’ para hacer nuestros análisis.
http://idee.es/

Espero que os resulte interesante.

Un saludo cordial,

Alberto
Geógrafo/ Máster SIG UAH/ Diseñador Multimedia

Advertisements

DTM validation using Google Earth (and RMSE extraction)

2015/03/10

Hi guys,

Surfing the internet is great when you need to figure out something. I needed to validate some DTM from unknown sources against an also unknown source (but at least a kind of reliable one, Google Earth).

All we need is

  • Google Earth
  • TCX converter
  • ARcGIS
  • Excel

This is the procedure i have followed:

  1. First of all we draw a path over our AOI using Google Earth, we save this as KML,
  2. This KML is opened by TCX converter, added heights and exported as CSV,
  3. CSV is imported by ArcGIS,
  4. We use the tool ‘extract multi values to points‘ to get in the same table the values of our DTM and the values from Google Earth,
  5. We use Excel to calculate the RMSE and get a quantitative result,

These are the values in our DTM

dtm-validation-02

This is the path we have to draw in Google Earth

dtm-validation-03

Using TCX converter we get the heights out of Google Earth’s DTM

dtm-validation-01

Using the tool ‘extract multi values to points‘ we get the heights out of our DTM

dtm-validation-04

We measure the differences and extract the RMSE.
Are we within our acceptance threshold or expected level of accuracy?.

You guys have to figure this out for yourselves!!!

Lost regarding RMSE calculation?. Think you have to take a look at this other post.

dtm-validation-05

dtm-validation-06

Hope you guys have enjoyed this post, if so, don’t forget sharing it.

Alberto Concejal
MSc GIS and QCQA expert (well this is my post and i say what i want :-))

Vulnérabilité de la population – Analyse SIG

2013/03/17

analisis_sig_gis

An ancien analyse accompli il y a long temps mais toujours d’actualité. En espagnol.

Data acquisition: How do I know if this river is been well acquired?

2010/06/14

I’ve already entered my river but my imagery was in 2D so… was it well acquired?…  First of all, I import my shape (shp) file into Global Mapper (what a great sofware!) and export my vector file as a KML.

Import my river.kml file into my brand new Google Earth 5.2 or just double-click it in his location… easyest impossible!.

Select it and use ‘show elevation profile’,  a very useful new tool for these purposes…

And that’s it, constant altitude, almost perfect!.

Hope you have considered it interesting:-)

Alberto

GIS+Architectural scenaries. Awesome!

2010/06/12

Even from scratch or from dgn/dxf vectorial format’s contour lines you create your own scenario.

Then import your model previously created using Sketch-up (this time i used google’s 3d warehouse, thank you Dilbert).

Stamp your house using sketch-up sandbox tools.

Then fur your scenario as if it was grass…

A little of photoshop like clouds and thats it!

Alberto Concejal
geographer, 3d designer & 3D GIS technician
albertoconcejal [at] gmail.com

Geovisualization, 3D models and more!

2009/08/17

Here you will be able to see some of my latest 3D stuff… A compilation of 3D models, flythroughs and graphic resuorces available… All you need regarding 3D scenarios (heights datasets, satellite imagery and 3D models) and Video Edition… Are you guys thinking about doing something like this?. Please contact me.

Alberto Concejal
BA Geography
MSc GIS and Remote Sensing
GIS Technician
albertoconcejal -at -gmail.com

One more 3D building. Avenida de la Vega 28108. Restaurante Asiático SHENG. Madrid, Spain.

2009/08/15

I used to have lunch every thrusday there, at the ‘Restaurante Asiático SHENG’. I strongly recommend you ‘entremeses’ (In China you will find them as ‘dim-sum’) and Cantonese duck or Hong Kong duck (this was slightly spicy thou).  Very good food, very fast service and pretty cheap menu: 10,7 €… ideal for an IT worker!.

chino02

These views were rendered using ‘V-RAY’ for Sketch-up.

chino03

avenida_de_la_vega_03

And now, Let’s go to Google Earth!

avenida_de_la_vega_04

avenida_de_la_vega_05

(I have modified my kml using a extruded placemark we talked about a few posts ago).
Now Let’s have our business in 3D!!!!!!!!!!!!!!!.
Hope you like it.
Alberto
BA Geography
MSc GIS and Remote Sensing
GIS Technician
albertoconcejal -at -gmail.com

News: Amazing Helsinki 3D!

2009/08/13

Navigating all over the world within Google Earth I have just discovered a brand new 3d layer in Helsinki, Finland.  Almost every building around makes this scenario very realistic… You just have to click on ‘3d buildings’  and it will show you this incredible layer… Does anybody know a WMS map to use it here?.

helsinki01

helsinki02

helsinki03

Hope you like them,

Alberto

Vicalvaro Buildings 3D. Madrid, Spain.

2009/08/11

And Now I would like to add one more set of buildings around my house. This is a block of flats in Vicálvaro, Madrid, Spain. This is supposed to be ‘Valderribas’ area… hope you like them!

vic_09

vic_08

vic_05

vic_06

vic_07

Creating and personalizing KML code (placemarks).

2009/08/11

First of all, what is KML?. KML is a file format used to display geographic data in an Earth browser, such as Google Earth, Google Maps, and Google Maps for mobile. You can create KML files to pinpoint locations, add image overlays, and expose rich data in new ways. KML is an international standard maintained by the Open Geospatial Consortium, Inc. (OGC). You can choose wether authoring directly from Google Earth itself or you can try to understand the code and doing it by yourself… You can draw placemarks (using descriptive HTML to personalize them), ground overlays, paths, polygons… Let’s start with the placemark:

-> Simple placemark

<?xml version=”1.0″ encoding=”UTF-8″?>
<kml xmlns=”http://www.opengis.net/kml/2.2″&gt;
  <Placemark>
    <name>Simple placemark</name>
    <description>Attached to the ground. Intelligently places itself
       at the height of the underlying terrain.</description>
    <Point>
      <coordinates>-122.0822035425683,37.42228990140251,0</coordinates>
    </Point>
  </Placemark>
</kml>

simpleplacemark

  • An XML header. This is line 1 in every KML file. No spaces or other characters can appear before this line.
  • A KML namespace declaration. This is line 2 in every KML 2.2 file.
  • A Placemark object that contains the following elements:
    • A name that is used as the label for the Placemark
    • A description that appears in the “balloon” attached to the Placemark
    • A Point that specifies the position of the Placemark on the Earth’s surface (longitude, latitude, and optional altitude)
  • -> Floating placemark

    <?xml version=”1.0″ encoding=”UTF-8″?>
    <kml xmlns=”
    http://www.opengis.net/kml/2.2” xmlns:gx=”http://www.google.com/kml/ext/2.2” xmlns:kml=”http://www.opengis.net/kml/2.2” xmlns:atom=”http://www.w3.org/2005/Atom“>
    <Document>
     <name>Floating placemark.kml</name>
     <Style id=”downArrowIcon”>
      <IconStyle>
       <Icon>
        <href>http://maps.google.com/mapfiles/kml/pal4/icon28.png</href&gt;
       </Icon>
      </IconStyle>
     </Style>
     <Placemark>
      <name>Floating placemark</name>
      <description>Floats a defined distance above the ground.</description>
      <LookAt>
       <longitude>-122.0839597145766</longitude>
       <latitude>37.42222904525232</latitude>
       <altitude>0</altitude>
       <range>500.6566641072245</range>
       <tilt>40.5575073395506</tilt>
       <heading>-148.4122922628044</heading>
      </LookAt>
      <styleUrl>#downArrowIcon</styleUrl>
      <Point>
       <altitudeMode>relativeToGround</altitudeMode>
       <coordinates>-122.084075,37.4220033612141,50</coordinates>
      </Point>
     </Placemark>
    </Document>
    </kml> 

    floatingplacemark

    -> Extruded placemark

    <?xml version=”1.0″ encoding=”UTF-8″?>
    <kml xmlns=”
    http://www.opengis.net/kml/2.2” xmlns:gx=”http://www.google.com/kml/ext/2.2” xmlns:kml=”http://www.opengis.net/kml/2.2” xmlns:atom=”http://www.w3.org/2005/Atom“>
    <Document>
     <name>Extruded placemark.kml</name>
     <Style id=”globeIcon”>
      <IconStyle>
       <Icon>
        <href>http://maps.google.com/mapfiles/kml/pal3/icon19.png</href&gt;
       </Icon>
      </IconStyle>
      <LineStyle>
       <width>2</width>
      </LineStyle>
     </Style>
     <Placemark>
      <name>Extruded placemark</name>
      <description>Tethered to the ground by a customizable
              &quot;tail&quot;</description>
      <LookAt>
       <longitude>-122.0845787421525</longitude>
       <latitude>37.42215078737763</latitude>
       <altitude>0</altitude>
       <range>365.2646606980322</range>
       <tilt>40.55750733918048</tilt>
       <heading>-148.4126684946234</heading>
      </LookAt>
      <styleUrl>#globeIcon</styleUrl>
      <Point>
       <extrude>1</extrude>
       <altitudeMode>relativeToGround</altitudeMode>
       <coordinates>-122.0857667006183,37.42156927867553,50</coordinates>
      </Point>
     </Placemark>
    </Document>
    </kml>

    extrudedplacemark

    If instead of regular <description>

    <description>Attached to the ground. Intelligently places itself
           at the height of the underlying terrain.</description>

    simple

    you use the CDATA element, you can write HTML and avoiding Google Earth from parsing the code incorrectly:

     <description>
            <![CDATA[
              <h1>CDATA Tags are useful!</h1>
              <p><font color=”red”>Text is <i>more readable</i> and
              <b>easier to write</b> when you can avoid using entity
              references.</font></p>
            ]]>
          </description>

     cdata